This project is designed to explore the role of specific lipoproteins and apoproteins as well as the role of coagulation factors and platelets in the sequential steps involved in the pathogenesis of atherosclerosis. This study will include the isolation and characterization of lipoproteins and apoproteins in the pigeon using the WC-2 breed of pigeons which develops localized areas of atherosclerosis spontaneously with increase in age. We will attempt to localize these plasma factors at all stages of atherosclerosis. The atherosclerosis-resistant Show Racer pigeon will be used as a control. Techniques for localization will include the use of immunofluorescence at the histologic level as well as immunoelectron microscopy. It is the goal of this study to precisely define the role of these plasma factors in the development and progression of atherosclerotic plaques in the arterial wall and, thus, contribute a better understanding of the pathogenesis of atherosclerosis.